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worked, differed in a very fundamental way, as pathogenes, from those 

 which I am studying, his forms being intracellular (except as regards 

 the first cell invaded), and not at once killing the adjacent cells. That 

 is, the condition pictured is much like that presented by Albugo, Perono- 

 spora, Puccinia, etc., except for the absence of haustoria. The forms 

 with which I deal, on the other hand, though they enter through the middle 

 lamellae, immediately become intracellular and at once kill the protoplast 

 of the invaded cell, and proceed similarly with other cells. These differing- 

 conditions, if substantiated by further study, probably indicate funda- 

 mental differences in the fungi in regard to their production of toxins or 

 enzymes, and certainly indicate an entirely different type of pathogenicity. 

 In these early stages the disease is properly a spot and not a rot. Whether 

 it will develop into a true, general rot depends upon conditions. Phenomena 

 like those described under the present heading, though differing in de- 

 tail, were noted with H. Nos. 6, 8, 9, 14, 21, 36, 39, 40, and 41. 



Action of various strains of Helmintkosporium on wheat shoots. Tests 

 in rag doll, at medium moisture, with H. No. 1 and H. No. 3 gave at 2 

 days 100% infection for both; at 6 days there was no appreciable difference 

 between the two; while at 10 days all shoots were rotten under H. No. 1 

 and some, but not so many, under H. No. 3. The test was repeated with 

 14 strains of Helminthosporium. All strains at 2 days showed 100% 

 infection; the controls, no infection. The infection phenomena with all of 

 these strains were all of the character described on pages 128, 129, showing 

 penetrating mycelium, "callus," etc. At 6 days H. Nos. 1, 4, 5, 8, 13-16, 20, 

 and 21 had all produced some rot. The roots also were distinctly yel- 

 lowed by H. Nos. 15 and 16, while H. No. 20 showed less rotting than 

 the other numbers mentioned above. H. Nos. 29 and 39 produced no 

 rotting, and the lesions were visible only through a lens, but thus viewed, 

 showed 100% infection, as indicated by the usual infection phenomena. 

 H. Nos. 3, 6, 9, 17, and 18 remained local, as at 2 days. H. No. 29, a 

 Helminthosporium with geniculate conidia, germinated abundantly from 

 both ends of the conidium, and on wheat produced many penetrating 

 mycelia and an abundant mycelium within the host, though the mycelial 

 invasion reached only a few cells, and while extending for a considerable 

 distance lengthwise, made but little progress laterally. The appressoria 

 were usually pyriform, as was also the penetrating mycelium, differing 

 thus from H. No. 1 (Fig. 17). Similar tests were made with three saltants, 

 M6, M8, and M38. Notes at 2 days showed 100% infection, and at 6 

 days much rot by M6, and considerable rot by the other two. 



